A Machine Type Communication (MTC) User Equipment (UE), also called as a Machine to Machine (M2M) user communication equipment, is a main application form of the present Internet of things. Low power consumption and low cost are important guarantees for its large-scale application. M2M equipment already deployed on the market is mainly based on a Global System of Mobile Communication (GSM). In recent years, due to improvement of spectral efficiency of Long Term Evolution (LTE)/LTE-Advanced (LTE-A), more and more mobile operating companies select LTE/LTE-A as an evolution direction of wideband wireless communication systems in the future. Various kinds of LTE/LTE-A-based M2M data services will be more attractive. An M2M service may be actually converted from a GSM to an LTE system only when cost of LTE-M2M equipment is lower than an MTC UE of the GSM.
In a related technology, main alternative methods for reducing cost of an MTC UE include: reducing a number of receiving antennae of the UE, reducing a baseband processing bandwidth of the UE, reducing a peak rate supported by the UE, adopting a half-duplex mode and the like. Cost reduction means performance reduction, however, a requirement on cell coverage of an LTE/LTE-A system is not allowed to be lowered. In this case, an MTC UE adopting a low-cost configuration may meet a coverage performance requirement of an existing LTE UE by adopting some measures. In addition, an MTC UE may be at a location such as a basement and a corner of a wall, and may be located in a scenario severer than an ordinary LTE UE. For compensating coverage reduction caused by penetration loss, part of MTC UEs requires performance to be improved more, so that it is necessary to perform uplink and downlink Coverage Enhancement (CE) on part of MTC UEs for such a scenario. How to ensure access quality of a user is the first problem to be considered, and it is necessary to perform enhanced design on random access signaling (also called as a Message 1 (Msg1)) of an LTE/LTE-A system to ensure that an MTC UE may normally access the system.
Location information of a Physical Resource Block (PRB) occupied by a Random Access Response (RAR) (also called as a Msg2) in an LTE/LTE-A system is included in Downlink Control Information (DCI) and sent through a Physical Downlink Control Channel (PDCCH). In addition, the DCI further includes a 16-bit Cyclic Redundancy Check (CRC), and the CRC is further scrambled by adopting a 16-bit Random Access Radio Network Temporary Identity (RA-RNTI), a scrambling manner being:ck=(bk+ak)mod 2 k=0,1, . . . ,15,
where bk is a (k+1)th bit in the CRC, ak is a (k+1)th bit in the RA-RNTI and ck is a (k+1)th bit generated after scrambling.
A UE receives an RAR and obtains uplink time synchronization and an uplink resource, but may not be determine at this moment that the RAR is sent not to another UE but to the UE. This is because there exists such a probability that different UEs sends the same random access sequence on the same time-frequency resource and they may receive the same RAR through the same RA-RNTI. Moreover, the UE may also not know about whether there is another UE using the same resource for random access or not. Thus the UE needs to solve such a random access conflict by a subsequent Msg3 and Msg4.
The Msg3 is a first message transmitted on a Physical Uplink Shared Channel (PUSCH) by adopting a Hybrid Automatic Repeat Request (HARQ) mechanism on the basis of uplink scheduling. In an initial random access process, it is a Radio Resource Control (RRC) connection request message (RRCConnectionRequest) transmitted in the Msg3, and if different UEs receive the same RAR, they may obtain the same uplink resource and simultaneously send the Msgs3. For distinguishing different UEs, a UE-specific Identifier (ID) may be contained in the corresponding Msg3 to distinguish different UEs, and in the case of the initial access, this ID may be an S-Temporary Mobile Subscriber Identity (S-TMSI) (if existing) of the UE or a 40-bit value which is generated randomly.
The UE starts a competition elimination timer immediately after sending the Msg3 (this timer is required to be restarted every time when the Msg3 is retransmitted subsequently), and the UE needs to monitor a contention resolution message (ContentionResolution, Msg4) returned to it by an Evolved Node B (eNB) within the time of the timer.
If the UE receives the Msg4 returned by the eNB within the time configured by the competition elimination timer and a UE ID contained therein is consistent with that reported to the eNB by the UE in the Msg3, the UE considers that it wins in this random access conflict and succeeds in random access, and sets a temporary Cell Radio Network Temporary Identifier (C-RNTI) obtained in the RAR to be own C-RNTI. Otherwise, the UE considers that this access fails and re-executes a random access retransmission process.
For ensuring that an MTC UE may normally access a system, it is also necessary to perform enhanced design on a Msg1. Msg2, Msg3 and Msg4 of an LTE/LTE-A system to ensure that the MTC UE may normally access the system.
For the problem of low quality of access of a UE to an LTE % LTE-A system in the related technology, there is yet no effective solution.